fast automerge: base implementation

app/models/project/hooks_trait.rb

@@ -101,6 +101,9 @@ module Project::HooksTrait
       # Execute web hooks
       self.execute_web_hooks(oldrev, newrev, ref, user)
+
+      # Create repo satellite
+      self.create_repo_satellite unless self.satellite_exists?
     end
   end
 end

app/models/project/repository_trait.rb

@@ -37,6 +37,23 @@ module Project::RepositoryTrait
       end
     end
+    def path_to_repo_satellite
+      File.join(Rails.root, "tmp", "repo_satellites", self.path)
+    end
+
+    def satellite_exists?
+      File.exist? path_to_repo_satellite
+    end
+
+    def create_repo_satellite
+      `git clone #{url_to_repo} #{path_to_repo_satellite}`
+      Dir.chdir(path_to_repo_satellite) do
+        primary_branch = Grit::Repo.new(".").heads.first.name #usually it`s master
+        `git checkout -b __parking_branch`
+        `git branch -D #{primary_branch}`
+      end
+    end
+
     def write_hook(name, content)
       hook_file = File.join(path_to_repo, 'hooks', name)

lib/gitlab_merge.rb

 class GitlabMerge
-  attr_accessor :project, :merge_path, :merge_request, :user
+  attr_accessor :project, :merge_request, :user
   def initialize(merge_request, user)
     self.user = user
     self.merge_request = merge_request
     self.project = merge_request.project
-    self.merge_path = File.join(Rails.root, "tmp", "merge_repo", project.path, merge_request.id.to_s)
-    FileUtils.rm_rf(merge_path)
-    FileUtils.mkdir_p merge_path
   end
   def can_be_merged?
-    pull do |repo, output|
+    process do |repo, output|
       !(output =~ /Automatic merge failed/)
     end
   end
   def merge
-    pull do |repo, output|
+    process do |repo, output|
       if output =~ /Automatic merge failed/
         false  
       else 
@@ -27,19 +24,20 @@ class GitlabMerge
     end
   end
-  def pull
+  def process
     Grit::Git.with_timeout(30.seconds) do 
       File.open(File.join(Rails.root, "tmp", "merge_repo", "#{project.path}.lock"), "w+") do |f|
         f.flock(File::LOCK_EX)
         
-        self.project.repo.git.clone({:branch => merge_request.target_branch}, project.url_to_repo, merge_path)
-        unless File.exist?(self.merge_path)
-          raise "Gitlab user do not have access to repo. You should run: rake gitlab_enable_automerge"
+        unless project.satellite_exists?
+          raise "You should run: rake gitlab_enable_automerge"
         end
-        Dir.chdir(merge_path) do
+        Dir.chdir(project.path_to_repo_satellite) do
           merge_repo = Grit::Repo.new('.')
+          merge_repo.git.sh "git fetch origin"
           merge_repo.git.sh "git config user.name \"#{user.name}\""
           merge_repo.git.sh "git config user.email \"#{user.email}\""
+          merge_repo.git.sh "git checkout -b #{merge_request.target_branch} origin/#{merge_request.target_branch}"
           output = merge_repo.git.pull({}, "--no-ff", "origin", merge_request.source_branch)
           yield(merge_repo, output)
         end

lib/tasks/gitlab/enable_automerge.rake

@@ -6,6 +6,13 @@ namespace :gitlab do
         git.admin_all_repo
       end
+      Project.find_each do |project|
+        if project.repo_exists? && !project.satellite_exists?
+          puts "Creating satellite for #{project.name}...".green
+          project.create_repo_satellite
+        end
+      end
+
       puts "Done!".green
     end
   end